Embodiments of the present invention relate generally to servo control systems, and more particularly servo control system with compensation for acoustic resonance modes.
Disk drives are widely used in computers and other electronic devices for the storage and retrieval of data. In the past, there has been a focus on improving disk drive performance by minimizing seek time during reads and writes. As a result, seek operations have traditionally been performed as quickly as possible. In order to maximize disk drive performance, disk drive manufacturers have generally sought to minimize seek time by employing a seek profile known as a performance seek profile or a bang-bang seek profile. Such a performance seek profile typically involves a head subjected to instantaneous maximum acceleration until the head reaches a maximum velocity, which is held until the head is subjected to maximum deceleration.
Such a performance seek profile has come to be known as a bang-bang seek profile, because the actuator first moves the head with maximum acceleration, and then later moves the head with maximum deceleration. By controlling the actuator to move the head with maximum acceleration and deceleration, noticeable levels of acoustic noise are generated due to vibration introduced to an actuator arm assembly on which the head is mounted as a result of the instantaneous acceleration and deceleration by the actuator.
More recently, there has been a recognition that when the mechanical components of a disk drive are moved as quickly as possible to minimize seek time, acoustic noise is generated that can be annoying and even worrisome to end users. Some levels of noise have become problematic, particularly in applications such as digital video recorders (DVRs), which are often used in an occupied, quiet room in which disk drive noises are unexpected, such as a living room or bedroom, leading to end user dissatisfaction with some disk drives. Accordingly, there is a need for disk drives and methods that can operate more quietly.